unknown outgoing tcp traffic - should I be worried?

I noticed recently almost continuous activity on my Belkin router for
one of the two Pc's connected to it.

I am running Peerguardian2 and it shows tcp traffic originating from
the PC to various destinations


each entry on the log shows an increment on the port of my PC

source destination


If I attempt to block the destination IP in Peerguardian the traffic
continues with my port number incrementing but with a different
destination IP


Any idea what is causing this and how to cure it? and is it risky to
allow this to continue, I can use the other PC on the network ok and
don't see the same sort of activity from that one.